Enteral feeding is known as a method for administering nutrition and drugs to a patient without relying on oral administration. In enteral feeding, liquids such as nutrients, liquid food, and drugs (generally called “enteral nutrients”) are administered to a patient via a transnasal catheter that has been inserted through the patient's nasal cavity and into their stomach or duodenum, or via a PEG (Percutaneous Endoscopic Gastrostomy) catheter that has been inserted into a gastrostomy formed in the patient's abdomen. The liquid to be administered to the patient is stored in a container. A bendable tube (referred to hereinafter as a “container-side tube”) is connected to the outlet port of the container. The downstream end of the container-side tube is connected to the upstream end of a catheter that has been inserted into the patient (transnasal catheter, PEG catheter, or the like), or the upstream end of a bendable tube that is connected to the catheter (collectively referred to hereinafter as a “patient-side tube”). In general, a connector tool made up of a male connector and a female connector is used to connect the container-side tube and the patient-side tube. Conventionally, the male connector is provided at the downstream end of the container-side tube, and the female connector is provided at the upstream end of the patient-side tube (e.g., see Patent Document 1).
If the liquid administered in enteral feeding is a liquid that has a low viscosity, problems occur, such as the liquid flowing backwards from the stomach to the esophagus and developing into pneumonia, or the patient suffering from diarrhea caused by moisture in the liquid not being sufficiently absorbed in the body. In view of this, in enteral feeding, the liquid is often given a higher viscosity (i.e., semi-solidified) by the addition of a thickening agent or a thickener, for example. Such a liquid that has been given a higher viscosity has a low fluidity, and thus has a high resistance when passing through a tube. Accordingly, when a liquid that has been given a higher viscosity is administered to a patient, pressure is applied to the liquid to pressure-feed it.
For this reason, there is desire for the connector tool that connects the container-side tube and the patient-side tube to include lock mechanisms that engage with each other in order to be able to withstand the pressure applied to the liquid. In view of this, international standard ISO 80369-3 regarding nutrition-related medical equipment has been given consideration for the international standardization of male connectors and female connectors for use in such applications.
As shown in FIGS. 24A and 24B, a male connector 910 under consideration as ISO 80369-3 has a tubular male luer 911 and an outer tube 913 that surrounds the male luer 911. An outer circumferential face 912 of the male luer 911 is a tapered face whose outer diameter decreases as it approaches the tip (a so-called male tapered face). A channel 917 that passes through the male luer 911 along the lengthwise direction thereof is formed in the male luer 911. Female threading 916 is formed in the inner circumferential face of the outer tube 913 that opposes the male luer 911.
On the other hand, as shown in FIGS. 25A and 25B, a female connector 920 under consideration as ISO 80369-3 has a cylindrical insertion portion (female luer) 921 into which the male luer 911 is inserted. An inner circumferential face 922 of the insertion portion 921 is a tapered face whose inner diameter increases as it approaches the tip (a so-called female tapered face). Male threading 926 is formed on the outer circumferential face of the insertion portion 921.
The male connector 910 and the female connector 920 are connected by inserting the male luer 911 into the insertion portion 921 and screwing the female threading 916 and the male threading 926 together. Since the outer circumferential face 912 of the male luer 911 and the inner circumferential face 922 of the insertion portion 921 are tapered faces that have the same taper angle, they come into liquid-tight surface contact with each other. The female threading 916 and the male threading 926 that are screwed together constitute lock mechanisms for locking the connected state of the male connector 910 and the female connector 920. The male connector 910 and female connector 920 provide a connection having excellent liquid-tightness (property of preventing the leakage of a liquid from the connection portion of the male connector and the female connector even if pressure is applied to the liquid) and excellent connection strength (property of preventing separation of the connected male connector and female connector even if pulling force is applied).
In the international standard ISO 80369-3, consideration has been given to providing the male connector 910 at the upstream end of the patient-side tube and providing the female connector 920 at the downstream end of the container-side tube in order to prevent mistaken connection with a connector used in a field other than enteral nutrition.